The N-Ferno 6990 Hand Warmer Packs are long-lasting and air-activated, instantly delivering up to 12 hours of heat. Theyre great for placing in your jacket pockets, gloves or other warming accessories. Each box includes 40 individually sealed pairs of warmers. Once activated, place the long-lasting hand warmer inside a pocket or gloves. Theyre also easy to insert into built-in pockets in thermal accessories such as the N-Ferno 6980 Hand Warmer Muff, N-Ferno Hard Hat Liners or ProFlex 825WP Winter Work Gloves. To activate, simply open the pack. The all-natural ingredients will begin to heat up as soon as theyre exposed to oxygenno batteries required. You can also shake the pack to speed up the warming process. The N-Ferno Hand Warmer packs are non-toxic and made with all-natural ingredients. Plus, theyre disposable and compact for easy use on the go. Packs are not reusable and should be disposed of after each use. LONG LASTING HEAT - Hand warmer packs keep hands free from chill for up to 12 hours. COMPACT - Small and low-profile to easily fit into gloves or jacket pockets. SIMPLE & INSTANT ACTIVATION - All-natural ingredients begin to heat up as soon as you open the pack (no batteries required). GREAT FOR USE WITH THERMAL ACCESSORIES - Easily insert into built-in pockets in thermal accessories for added warmth. WORKDAY TO WEEKEND - For cold-weather use on the job or during outdoor recreation like hunting and hiking. NON-TOXIC - Made with all-natural ingredients. AVAILABLE IN 40 OR 100 PACKS - Includes 40 or 100 individually sealed pairs of warmers.